Significant benefits can be realized from electrochemically measuring analytes in fluidic samples (i.e., biological or environmental). For example, diabetic treatment with self-monitoring blood glucose (SMBG) devices and systems contributes to improving glycemic control and attenuating diabetes-related morbidity. Therefore, the accuracy of SMBG devices and systems is important for optimal glycemic control.
The accuracy, however, of present methods of electrochemically measuring analytes such as glucose can be negatively affected by a number of interferents including antioxidants or other reducing agents. Because of their benefits, there is an increasing number of medical uses, as well as off-label therapies and alternative medicine procedures, in which megadoses of antioxidants are administered by injection or intravenously. For example, burn patents often are treated with parenteral doses of ascorbate, resulting in blood plasma levels of 40 mg/dL or more. There also are alternative cancer therapies that prescribe much larger doses, resulting in ascorbate levels as high as 400 mg/dL. Unfortunately, high doses of antioxidants such as ascorbate can interfere with the electrochemical response of SMGB devices and systems and can cause them to report falsely elevated glucose concentrations, which presents a significant disadvantage for an individual with diabetes receiving an antioxidant therapy. Specifically, if an individual is in a euglycemic state, but responds to the falsely elevated glucose concentration by administering insulin, this could result in hypoglycemia and/or death. The Food and Drug Administration suggests that ascorbate interference exists for some electrochemical assays even at 3 mg/dL of ascorbate.
Current electrochemical SMBG methods, devices and systems provide individuals having diabetes advantages with respect to convenience; however, there remains a need for improved methods of electrochemically measuring an analyte in a fluid sample with additional quality checks for the presence of interferents such as an antioxidant or for detecting a failure with the biosensor reagent system.